This invention relates generally to the field of syringes and, more particularly, to syringes used with viscoelastic agents.
During surgery, particularly ophthalmic surgery, various viscoelastic agents may be introduced into the surgical site. These agents generally are expressed into the surgical site out of a syringe and through a relatively thin cannula. The pressures exerted on the syringe to express the viscoelastic agent can be very high due to the high viscosity of the viscoelastic agents. Glass syringes have relatively small, fragile finger flanges. As a result of this combination of high expression forces and fragile flange, syringes used with viscoelastic have a tendency to break. Prior art syringes intended for use with viscoelastic agents, such as described in U.S. Pat. No. 4,540,405 (Miller, et al.) and U.S. Pat. No. 5,876,379 (Beauvais, et al.), have provided a flange extender that provides a better grip on the relatively small syringe so that sufficient force can be applied to express the viscoelastic agent without breaking the syringe. Recently, however, the use of pressurized air to express the viscoelastic agent from the syringe rather than manual activation of a plunger has become popular. These prior art syringe flange extenders do not provide a connection for a pressurized air source.
Accordingly, a need continues to exist for an automated means of delivering viscous materials from glass syringes by providing a connection to a source of pressurized air for expression of the viscous material.